The Achilles’ Heel of 3D Printing

Why ‘additive manufacturing’ isn’t expected to take over large scale industrial production any time soon

We think we know what makes things expensive to make

We’ve all got a surprisingly clear idea of exactly what it is that makes something really difficult and hideously expensive to produce: serious complexity.

The cost of just about everything we make goes up exponentially as the physical functionality of its innards gets more sophisticated (big things containing motors and gears, for example, are rarely ‘as cheap as chips’: even silicon chips are only cheap because, despite their enormous complexity, we can and do make them in enormous quantities).

But there’s an exception

In 3D printing, our whole intuitive concept of ‘cost related to complexity’ is turned on its head.

The cost of creating things using a 3D printer ‘goes down with complexity’: the more complex the item being printed, the less it costs to print it.

Usually, the more complicated something is (i.e., the more parts and sub-parts it is made from and the more complex the resulting assembly process happens to be) the more it costs to make.

But, bizarrely enough, 3D printing doesn’t tend to ‘struggle’ in any cost-incurring way based upon how intricate the design of the item being manufactured happens to be: a 3D printer prints a complex 3D shape just as easily as it prints a simple one.

Complexity actually reduces 3D printing costs, are you serious?

In fact, because the cost of printing an object depends almost entirely upon nothing more than the quantity of ‘ink’ (and comparatively little electricity) the more complex the shape, the more ‘air’ there is between the parts (designers call inter-component-spaces ‘voids’) the less 3D printer ink (which is usually plastic, but can sometimes be metallic) that is required to create the printed object and so, contrarily, the more complex the object, the cheaper it is to print.

The notorious 3D printing ‘complexity paradox’

greater complexity = more + bigger voids = less ink = lower cost

The complexity paradox raises the following questions:

So if the one thing (complexity) that makes most things more expensive to make is unquestionably vanquished by 3D printing, why isn’t it ‘game over’ for all other forms of manufacturing?

How 3D printers work

A common variety of 3D printer is really just an ink jet printer (although there are many other types of 3D printer) which prints physical objects in layers by using thick ‘ink’ and by moving the print head backwards and forwards as well as from side to side (and also moving upwards as it completes printing each layer).

Ink yes, cartridge no

Unlike a conventional inkjet, the material that is used to ‘print’ the shape doesn’t come in a cartridge: the 3D printer has to be fed a very long, thin, curled-up strip of plastic that sticks out of the ‘extruder head’ at the top of the printer: it’s this strip that is the ‘3D ink’ and it’s called a ‘filament’.

The printer’s extruder head melts and then dispenses the resulting molten plastic of the filament through a nozzle, emerging as a fine, thread-like ‘dribbled squirt’ stripe of viscous, gooey ink that sets hard and fuses with the layer of ink below it as it cools (just imagine using an inkjet printer to write in frosting on a wedding cake (and yes, of course, ‘extrusion printing’ has actually been used to do this: it’s their versatility, cheapness and scope for rewarding personal inventiveness that is responsible for the current 3D printing craze).

And if 3D printing machines can currently be not just tens, but hundreds and often thousands of times cheaper to buy than their long-established industrial counterparts (which actually consist of not just single machines but of entire production lines, very often costing millions) why isn’t the manufacturing industry imploding as we all stop buying things and start making everything at home using devices that cost as little as $200?

What are the competitive advantages of conventional automated manufacturing?

Well, there are many challenges to 3D printing on an industrial scale, but the most significant and daunting of them relate to the fact that most of what is manufactured is made from parts that are ‘too many’, ‘too simple’ and made (and usually needed) ‘too fast’ for 3D printing to even come close to being competitive with existing manufacturing technologies.

How do manufacturing industry insiders view 3D printing?

3D printing, despite the ‘leading edge’ cachet associated with its technology, is ironically mostly seen by the manufacturing sector as a ‘cottage industry’ and a ‘craft’ (despite being fully accepted by them as an indispensable design and tooling resource) rather than as the destiny of of large scale manufacturing.

What sticks do they use to beat it with?

If you were wondering which unflattering terms manufacturing industry insiders use to characterise the shortcomings of 3D printing when compared to other forms of industrial production, you might want to check these out (well-informed manufacturing industry commentators are also well aware of the developments which address these issues, you can also check out the the ‘criticism responses’ sidebar, below):

cheapest 3D printers can make small, decorative knick-knacks, but not much else

just fun to watch

best for educational and hobby use

just cheap toys for making cheaper toys

just a designer’s fantasy about cutting out the middleman

a great solution still looking for truly applicable problems

serious cost issues on almost all large-scale applications

unresolved technical problems on most fronts

only really suitable for DIY or small startup usage

only serious design role is prototyping

only serious production role is for making molds

suited to the desktop or garage, not factory operation

CNC and robotics were also predicted to take over everything in manufacturing decades ago, but are still only niche

The primary challenge for 3D printing at the industrial scale is not that it is limited or ineffective (all of the above kinds of problems are rapidly yielding to extensive research).

The two differing optimisations

3D printing:

Produces objects with unconstrained geometric structural complexity as slowly as necessary and as cheaply as possible

Non-3D manufacturing:

Produces parts with unconstrained material composition requirements as quickly and accurately as possible

Does robotics have a role to play in the comparison?

Notice that trying to compare 3D and non-3D is asymmetric: 3D is more ‘holistic’ (except when it comes to fabrication multi-material composites, where non-3D is far less constrained) and that non-3D is more about ‘parts’ than objects, because 3D can offer the opportunity to print entire ‘multi-part objects’ (when the moving parts shortcomings of 3D printing are overcome) ‘in one go’ but in both 3D and non-3D, the ‘some assembly required’ issue can still arise, something which, in the context of automation, tends to introduce robotics, which, for the purpose of this article, I am classifying outside of both 3D printing and conventional manufacture, but at some point will need to be considered in the context of the following question:

Does ‘robotics combined with 3D printing’ change the comparison with conventional manufacturing’?

What about 3D and non-3D integration?

At this stage I can’t see how the robotic assembly issue necessarily affects the comparison, but it certainly does raise ‘integration-related process optimisation issues’ (i.e., integrating 3D printing and non-3D printing into the same manufacturing process) but I don’t see how this would introduce any ‘acceleration of 3D printing encroachment on non-3D manufacturing’ except in the probably comparatively rare situation where certain conventionally manufactured parts prove to be more suited to 3D printing (e.g. internal stress-bearing design optimisation)

3D printing’s biggest bugbears: simplicity, quantity and speed

It’s just that the unique combination of the primary advantage and disadvantage of 3D printing, namely ‘economical handling of complexity plus inherently slow operation’ are the precise opposite of (or at the very least, poorly aligned with) the imperatives that conventional manufacturing processes are optimised for: simplicity, quantity and speed.

Responses to criticisms of 3D printing

Slow for production? Yes, but it speeds up the design process tremendously

Does speed always matter? Not if the thing being printed is actually impossible (or too expensive) to make or obtain by other means

Niche only? Yes, but maybe the future is more niche that the present: mass production itself may become niche

Mostly small items only? You can actually build houses using 3D printing: also, creating giant 3D printers can be orders of magnitude cheaper than equipping any other fabrication process to produce big parts

Ok, so maybe the examples above are only exceptions, but you have to admit:

No matter how sophisticated an industrial-scale mass-produced product happens to be, most of the devices that make up its components are usually produced by manufacturing equipment which operates at tremendous rates of throughput: conventional manufacturing automation is all about making very large numbers of simple things extremely quickly (and accurately).

Volume and speed crush the complexity advantage

Hundreds of billions of plastic and metal parts are turned out in millions of industrial production lines around the globe every year, each of which is often produced in far less than a second if they are stamped out, often a few seconds or less if they are molded.

The typically noisy drumbeat of conventional manufacturing is the unmistakable sound of a completed part (but far more often, several) being ‘spat out': the more sedate, often inaudible drumbeat of 3D printing is the sound of just one more printed ‘ink-stripe’ of just one more layer among the many layers which need to printed before the part is finished.

Even the fastest 3D printing process is typically hundreds but usually thousands of times slower (often many hours per item, very rarely much less than half an hour) than its conventional manufacturing automation counterpart and there is no sign, despite notable recent speed improvements, that it is going to come anywhere near to catching up any time soon.

In the design world, the 3D revolution has already happened

The good news for 3D printing in terms of its future role in industrial processes is that 3D is by no means rendered inconsequential by this limitation as a production line resource.

Rapid prototyping of 3D models by industrial designers (notice how ‘rapid’ for design-turnaround means something quite different to rapid on the production line) happened to be how 3D printing began, and the strong prospects for continued reduction in the costs of 3D printers and advances in quality and flexibility of their output (and also in speed, but by no means to an extent where their production line limitations as identified above are expected to be significantly overcome in the short or even medium term) mean that almost the whole of the industrial design scene has been moving towards being 100% 3D printing-capable for some time now.

3D already has an important foothold inside manufacturing

On the production side, 3D technologies (including ‘subtractive’ CNC equipment such as milling machines, a relevant but quite different 3D technology, which also suffers from quite similar but not identical speed-versus-complexity trade-offs as 3D printing) play a growing role in helping to create molds, devices and components used in non-3D manufacturing.

But that won’t tip the balance: most manufacturing still needs to address speed requirements, not complexity

But for everything else, the ‘complexity handling advantage’ and the ‘speed disadvantage’ of 3D printing compared with conventional manufacturing technology almost exactly cancel one another out.

This means that when the complexity of the product being manufactured is low enough, 3D printing’s orders of magnitude of ‘complexity advantage’ all vaporize and volume and speed requirements become decisive.

Several thousand finished units could have already rolled off the conveyor belt of a comparatively modestly equipped production line, whilst each 3D printer is still toiling merrily away, less than half way through its first unit (unsurprisingly perhaps, nobody has yet built a production process using many thousands of 3D printers in order to address the speed issue by adopting ‘massively parallel 3D printing’).

What would need to happen in order for us to switch to 3D?

So, in order for 3D printing to substantially replace existing manufacturing technology, it looks like it would need:

3D printing to offer us a speed of operation that was at least one, probably two, but in most cases as many as three orders of magnitude faster than it is now, or

that the number of 3D printing machines used in manufacturing would grow exponentially and (dis?)proportionately (for one of several potential reasons, see the robotics and integration issues in the sidebar) or

that our need for (or ability to afford?) so many mass produced items would need to diminish (due to either reduced consumption or due to a widespread and unprecedented increase in the appetite for ‘mass customisation’?)

all factored into the same equation.

Until one of these major changes occurs, but 3D printing still remains enormously slower than conventional manufacturing, it is reasonable to anticipate that 3D printing will probably extend each of its current niches and almost certainly find itself a few more, but that large scale manufacturing can be expected to continue to be dominated by other, non-3D technologies.

Is this really a big deal?

If you need to get your head around the sheer scope of the challenge, just go to your local giant supermarket or hardware store and look at the tens of thousands of products: now look at all the jars, bottles and tins and their lids: all manufactured using automation, untold billions of plastic, metal and glass items produced worldwide, every day, none produced by anything resembling 3D printing. And remember: each of those containers, made in split seconds for pennies, still needs to be filled with things like yogurt or paint and then packaged: in the real world, manufacturing technology isn’t just about making things.

And what would happen if …?

It probably goes without saying that if we suddenly discovered a way to do 3D printing (probably using 3D technologies other than those in current use) that was anywhere near as fast as conventional manufacturing, the resulting revolution could quite possibly be as big as, if not bigger than the Internet.

A useful table showing the different 3D printing technologies in Wikipedia is included below:

42 Comments

Perhaps your assumptions are correct in the “toy” 3D printer category, but many of them (other than speed) do not hold true for the high end laser sintering tools. Also, if you replace “complexity” with “uniqueness” you’ll get a better picture of the optimal applications for current technology. It is totally misleading to apply the same conclusions to an $800 lumpy plastic crap maker and a $600k EOSINT that can produce high quality, high precision parts in a variety of “real” materials.

That’s the problem. An EOS is a wonderful machine, it does incredible things. But let’s not pretend that the Aluminium, the Nylon or other materials used in it are “real”. Yes, they use the same base component chemistry or metallurgy and yes, they have the same basic characteristics. But there it stops. Sintered nylon isn’t the same as injection moulded nylon. Sintered nickel bronze isn’t the same as cast or machined nickel bronze.

When it comes to prototyping (robots, enclosures, mechanical parts, etc, etc) there’s something wonderful about being able to print it out in a few hours, rather than waiting days or weeks for the part to arrive. And I can fix any errors same-day, prior to having the ‘real’ product mass manufactured.

My 3D printer allows a greater level of creativity and has sped up my development process beyond what I expected when I bought it.

Sure, it’s not a miracle cure-all, and not everyone will find it useful or fast enough for their needs, but I’ve had mine for less than a month and I feel it has more than paid for itself.

Go to the grocery store and work out how many 3D printers you’d need to be able to fill all the plastic, glass and metal containers with food, drink and other household consumables.

The machines that already do this (as well as those that make the containers) do it quickly cheaply and efficiently.

3D printers fill some excellent roles in industrial production. But to assume that all our consumption requirements are directly compatible with 3D printing technology only makes sense if you postulate a technology three orders of magnitude faster than anything we have today.

It wouldn’t at all surprise me if this is possible, but it would very much surprise me if it was possible soon.

I agree, but for many manufacturers the conclusion is beside the point. More products are going to emerge from small innovators now that they can inexpensively prototype small quantities of products. But once they prove economic viability, they’re still going to need professional, large scale manufacturing.

There is a definite business opportunity for small and medium manufacturers to specialize in transitioning from 3d printing at home to professional manufacturing.

I wrote a more in-depth response at http://blog.industrialinterface.com/2012/12/30/how-3d-printing-will-generate-business-for-production-manufacturers/

The niche market lays in parts replication and the exponential rate in which these parts become public domain.
Complex parts are prohibitively expensive to replicate by manual labour. The ability to play with hardness and materials that are superior in quality to the original parts are still not much explored for replicas.

Of course the real future of 3D printing is food printing… comming very soon

If 3D printers become a commodity item, then volume and speed are no longer important, because each household will not need high volumes of things nor will it care if they take a few hours to print. This technology is disruptive precisely because it brings inferior products to a class of consumer who has never had access to them before. Expect it to rapidly improve in quality and eventually take over alternative delivery methods.

This article represents the ‘old world’ looking at the ‘new world’ and saying “That’s never going to do what we do!” Well, no it isn’t, because this is a new business model. Rather than make a billion units, warehouse and distribute them, in the old ‘mass manufacturing’ model, the user downloads and prints ‘objects on demand’. It’s a totally different model. Saying it can’t do high-speed mass-manufacture is to disastrously miss the point . . .

I Believe article, “The Achilles’ Heel of 3D Printing ~ Innovation Investment Journal” ended up being spot on!
I actuallycouldn’t see eye to eye with u even more! At last looks like I personallyidentified a website worth browsing. Regards, Lupe

Talkina about 3D printing I can say that this is the best innovation for now. Because it opens wider opportunities to all of us. Now 3D printing is maybe costing too much, but in the future, after about 3-4 years when this thing will be available for everyone I think people will no go to fix theirs broken things but they will create another one.

The side that everyone can use different material to print model shows us that it is really universal thing. If we now can create real guns just from weapons 3D model, that some time ago was 2D model.. to cookies to eat for a Christmas..or clothes for fashion shows..

Also more and more people are talking about 3D printing use for medicine. I think this is extremely important to our lives.. to change them or make easier. I think that in the near future we will know how to print real heart with all of its functions and use it for people as an implant. or are there printed it yet ? Hope this innovation goes far..

Although it may be argued that mass production speed issues are an Achilles’ heel for 3D printing, one can also argue that the 3D printing revolution can sidestep the mass production process altogether. Although these smaller ‘toy’ 3D printers aren’t great at creating highly articulated items, when the complexity does come and prices for these printers fall, we could see 3D printers becoming common in family homes, meaning that a company no longer spends money on production and only has to sell a design that a user can print in their own home. Products on demand will revolutionize the supply chain because well, in the future there may not be one.

A lot of the critique has merit. However, we print custom cranial implants far more economically then can be machined with a biocompatible structural polymer. Every day we see great possibilities but the fusion of advanced materials, design and additive method must be integrated to bring forth high value solutions that folks will pay for. Of course all this needs to happen in real manufacturing environments that meet international QMS and such.

You’re so cool! I do not believe I’ve read through a single thing like this before.
So nice to discover somebody with a few original thoughts on this subject.
Really.. thank you for starting this up. This website is something that’s needed on the web, someone with some originality!streetdirectory :: Kasha ::

The important thing to digest here is not the current limitations of 3d printing, but how quickly those limitations will be addressed now that 3d printing is becoming mainstream. This newly commercialized and likely to boom industry, will be driven by massive competition and innovation in effort to win the almighty consumer dollar. That is the only great thing about capitalism… if there is money to be made, innovation follows.
These shortcomings of 3d printing are on the forefront of a hundred thousand business strategies right now; rest assured, solutions will follow. People will only become more and more excited by the prospect of highly customized, cheaper, more environmentally responsible products, and instant gratification without leaving their living room. Sorry to the manufacturing sector, but the threat is real. Inevitable.